ESSENDON has withheld sensitive information about the club's game-plan from its top-up players for fear of having opposition clubs steal its intellectual property.

With about 17 Bombers-listed players provisionally suspended over the club's 2012 supplements program, Essendon has been forced to rely on the services of up to 13 top-up players to fill its team during the NAB Challenge series.

James Polkinghorne (Brisbane Lions), Jordan Schroder (Geelong), Clint Jones (St Kilda), Mitch Brown (Geelong), Mitch Clisby (Melbourne), Jared Petrenko (Adelaide), James Magner (Melbourne) and Sam Michael (Brisbane Lions) are among the players who have been previously listed by an opposition AFL club.

Essendon assistant coach Mark Harvey said the club feared disclosing critical information to the top-up players in case other clubs approached them when their stints were over to learn secrets from the Bombers' game-plan.

"The interesting part is that it's very hard to simulate your game-plan when you have upwards of eight to 10 players who have just come into your club in the last two weeks," Harvey told SEN on Wednesday morning.

"Sometimes things like structure and the timing of what you need to do (has been problematic).

"How much information do you pass on with your strategy and tactics to these guys, knowing they might be around for a couple of weeks?

"That's been difficult."

Harvey said the club had decided the best course of action was to have separate meetings.

"We've had a couple of different meetings throughout the course of a week on those sorts of issues," Harvey said.

"But the (top-up) guys that we've got into the club have been fantastic in the way that they've conducted themselves and the way they've gone out and played."

AFL Anti-Doping Tribunal findings notwithstanding, a number of Essendon-listed players will head into the club's round one clash against the Sydney Swans without playing an official practice match.

Harvey said it has been tough to simulate game-like intensity at training and prepare the players for the premiership season.

"We hope that we're getting in somewhere near the game simulation that they'd be getting if they were playing in the NAB Challenge," Harvey said.

"As you know, they're not necessarily playing in their structural positions based on the training modes that we're doing at the moment.

"It's very hard from a game style to get the rhythm and what we need to do when we can't all play together."

Essendon meets Melbourne at Etihad Stadium in its last NAB Challenge hit-out on Friday night.

The Tribunal will hand down its verdict on the Essendon players on March 31 and if results do not fall the club's way it may be forced to retain some of the top-up players for the season proper.